Tissue sealing instrument with tissue-dissecting electrode

ABSTRACT

An electrosurgical instrument includes an elongated shaft extending distally from a housing and an actuating mechanism operably coupled to a proximal portion of the elongated shaft and configured to move the elongated shaft. First and second jaw members are coupled to a distal portion of the elongated shaft. The first jaw member is pivotable relative to the second jaw member between open and closed positions. An electrically conductive tissue sealing surface is disposed on each of the jaw members and is adapted to connect to a source of electrosurgical energy. A tissue-dissecting electrode is disposed on a distal end of at least one of the jaw members in spaced relation to the tissue sealing surface and is adapted to connect to a source of electrosurgical energy. An insulator couples the tissue-dissecting electrode to the jaw member and electrically insulates the tissue-dissecting electrode from the jaw member.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/538,137 filed Nov. 11, 2014, which claims the benefit of the filingdate of provisional U.S. Patent Application No. 61/932,978 filed Jan.29, 2014, the entire contents of each of which are incorporated hereinby reference.

INTRODUCTION

The present disclosure relates generally to the field of surgicalinstruments. In particular, the disclosure relates to an endoscopicelectrosurgical forceps capable of electrosurgically sealing tissue andelectrosurgically dissecting tissue.

BACKGROUND

Instruments such as electrosurgical forceps are commonly used in openand endoscopic surgical procedures to coagulate, cauterize and sealtissue. Such forceps typically include a pair of jaw members that can becontrolled by a surgeon to grasp targeted tissue, such as, e.g., a bloodvessel. The jaw members may be approximated to apply a mechanicalclamping force to the tissue, and are associated with at least oneelectrode to permit the delivery of electrosurgical energy to thetissue. The combination of the mechanical clamping force and theelectrosurgical energy has been demonstrated to join adjacent layers oftissue captured between the jaw members. When the adjacent layers oftissue include the walls of a blood vessel, sealing the tissue mayresult in hemostasis, which may facilitate the transection of the sealedtissue. A detailed discussion of the use of an electrosurgical forcepsmay be found in U.S. Pat. No. 7,255,697 to Dycus et al.

A bipolar electrosurgical forceps typically includes opposed electrodesdisposed on clamping faces of the jaw members. The electrodes arecharged to opposite electrical potentials such that an electrosurgicalcurrent may be selectively transferred through tissue grasped betweenthe electrodes. To effect a proper seal, particularly in relativelylarge vessels, two predominant mechanical parameters must be accuratelycontrolled; the pressure applied to the vessel, and the gap distanceestablished between the electrodes.

Both the pressure and gap distance influence the effectiveness of theresultant tissue seal. If an adequate gap distance is not maintained,there is a possibility that the opposed electrodes will contact oneanother, which may cause a short circuit and prevent energy from beingtransferred through the tissue. Also, if too low a force is applied thetissue may have a tendency to move before an adequate seal can begenerated. The thickness of a typical effective tissue seal is optimallybetween about 0.001 and about 0.006 inches. Below this range, the sealmay shred or tear and above this range the vessel walls may not beeffectively joined. Closure pressures for sealing large tissuestructures preferably fall within the range of about 3 kg/cm² to about16 kg/cm².

SUMMARY

The present disclosure relates to an electrosurgical apparatus andmethods for performing electrosurgical procedures. More particularly,the present disclosure relates to electrosurgically sealing anddissecting tissue.

The present disclosure describes an electrosurgical instrument fortreating tissue. The electrosurgical instrument includes an elongatedshaft extending distally from a housing and defining a longitudinalaxis. The electrosurgical instrument also includes an actuatingmechanism operably coupled to a proximal portion of the elongated shaft.The term “distal” refers herein to an end of the apparatus that isfarther from an operator, and the term “proximal” refers herein to theend of the electrosurgical forceps that is closer to the operator. Theactuating mechanism is moveable relative to the housing to move theelongated shaft along the longitudinal axis. An end effector is coupledto a distal portion of the elongated shaft. The end effector includesfirst and second jaw members. The first jaw member is pivotable relativeto the second jaw member between an open position and a closed position.An electrically conductive tissue sealing surface is disposed on each ofthe jaw members and is adapted to connect to a source of electrosurgicalenergy. The tissue sealing surfaces are configured to conductelectrosurgical energy through grasped tissue. A tissue-dissectingelectrode is disposed on a distal end of at least one of the jaw membersin spaced relation to the tissue sealing surface. The at least onetissue-dissecting electrode is adapted to connect to a source ofelectrosurgical energy and is configured to electrosurgically dissecttissue. An insulator couples the at least one tissue-dissectingelectrode to the jaw member and is configured to electrically insulatethe at least one tissue-dissecting electrode from the jaw member.

Additionally or alternatively, the at least one tissue-dissectingelectrode and at least one of the tissue sealing surfaces are configuredto generate a bipolar energy potential therebetween for dissectingtissue.

Additionally or alternatively, the at least one tissue-dissectingelectrode extends distally from a distal end of the at least one jawmember.

Additionally or alternatively, the at least one tissue-dissectingelectrode is configured to dissect tissue when the first jaw member isin the open position.

Additionally or alternatively, the at least one tissue-dissectingelectrode is configured to dissect tissue when the first jaw member isin the closed position.

Additionally or alternatively, at least one of the tissue sealingsurfaces includes a flex circuit disposed thereon configured toelectrically connect the at least one tissue-dissecting electrode to asource of electrosurgical energy.

Additionally or alternatively, the at least one tissue-dissectingelectrode is configured to be energized with a first polarity ofelectrosurgical energy and at least one of the tissue sealing surfacesis configured to be energized with a second polarity of electrosurgicalenergy.

Additionally or alternatively, the at least one tissue-dissectingelectrode is electrically deactivated during sealing of tissue graspedbetween the tissue sealing surfaces.

Additionally or alternatively, the end effector is configured toelectrosurgically dissect tissue contacted by the tissue-dissectingelectrode and at least one of the tissue sealing surfaces.

Additionally or alternatively, the electrosurgical instrument alsoincludes a stationary actuation member axially disposed within theelongated shaft and a camming slot disposed on the second jaw member.The stationary actuation member includes a cam pin mechanically coupledto a distal end thereof and the camming slot is configured to engage thecam pin to move the first jaw member between the open position and theclosed position upon movement of the elongated shaft along thelongitudinal axis.

Additionally or alternatively, the electrosurgical instrument alsoincludes a knife advanceable along the longitudinal axis through a knifechannel extending at least partially through the jaw members to cuttissue grasped therebetween.

Additionally or alternatively, the electrosurgical instrument alsoincludes a switch supported by the housing and engageable by theactuating mechanism to control delivery of electrosurgical energy from asource of electrosurgical energy to the end effector.

Additionally or alternatively, the second jaw member is mechanicallycoupled to a distal end of the elongated shaft and the first jaw memberis moveable relative to the second jaw member.

Additionally or alternatively, the at least one tissue-dissectingelectrode conducts a first polarity of electrosurgical energy and atleast one of the tissue sealing surfaces conducts a second polarity ofelectrosurgical energy.

Additionally or alternatively, the tissue sealing surfaces areconfigured to electrosurgically cut tissue grasped therebetween.

According to another aspect of the present disclosure, anelectrosurgical instrument is provided. The electrosurgical instrumentincludes an elongated shaft extending distally from a housing anddefining a longitudinal axis. The electrosurgical instrument alsoincludes an actuating mechanism operably coupled to a proximal portionof the elongated shaft. The actuating mechanism is moveable relative tothe housing to move the elongated shaft along the longitudinal axis. Anend effector is coupled to a distal portion of the elongated shaft. Theend effector includes first and second jaw members. The first jaw memberis pivotable relative to the second jaw member between an open positionand a closed position. An electrically conductive tissue sealing surfaceis disposed on each of the jaw members and is adapted to connect to asource of electrosurgical energy. The tissue sealing surfaces areconfigured to conduct electrosurgical energy through grasped tissue. Atissue-dissecting electrode is disposed on a distal end of the secondjaw member in spaced relation to the tissue sealing surface of thesecond jaw member. The tissue-dissecting electrode is adapted to connectto a source of electrosurgical energy and is configured toelectrosurgically dissect tissue using a bipolar energy potentialgenerated between the tissue-dissecting electrode and at least one ofthe tissue sealing surfaces. An insulator couples the tissue-dissectingelectrode to the second jaw member and is configured to electricallyinsulate the tissue-dissecting electrode from the second jaw member.

Additionally or alternatively, the tissue-dissecting electrode isconfigured to conduct a first polarity of electrosurgical energy, one ofthe tissue sealing surfaces is configured to generate a second polarityof electrosurgical energy, and the other tissue sealing surface isconfigured to be electrically deactivated.

According to another aspect of the present disclosure, anelectrosurgical system is provided. The electrosurgical system includesa source of electrosurgical energy and an electrosurgical instrumentoperably coupleable to the source of electrosurgical energy. Theelectrosurgical instrument includes an elongated shaft extendingdistally from a housing and defining a longitudinal axis. Theelectrosurgical instrument also includes an actuating mechanism operablycoupled to a proximal portion of the elongated shaft. The actuatingmechanism is moveable relative to the housing to move the elongatedshaft along the longitudinal axis. An end effector is coupled to adistal portion of the elongated shaft. The end effector includes firstand second jaw members. The first jaw member is pivotable relative tothe second jaw member between an open position and a closed position. Anelectrically conductive tissue sealing surface is disposed on each ofthe jaw members and is adapted to connect to a source of electrosurgicalenergy. The tissue sealing surfaces are configured to conductelectrosurgical energy through grasped tissue. A tissue-dissectingelectrode is disposed on a distal end of at least one of the jaw membersin spaced relation to the tissue sealing surface. The at least onetissue-dissecting electrode is adapted to connect to a source ofelectrosurgical energy and is configured to electrosurgically dissecttissue. An insulator couples the at least one tissue-dissectingelectrode to the jaw member and is configured to electrically insulatethe at least one tissue-dissecting electrode from the jaw member.

Additionally or alternatively, the source of electrosurgical energy isconfigured to deliver a tissue-cutting electrosurgical waveform to thetissue sealing surfaces for electrosurgically cutting tissue graspedtherebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentdisclosure and, together with the detailed description of theembodiments given below, serve to explain the principles of thedisclosure.

FIG. 1 is a perspective view of an electrosurgical forceps according toan embodiment of the present disclosure including a housing, anelongated shaft, and an end effector;

FIG. 2A is an enlarged, perspective view of the end effector of FIG. 1depicted with a pair of jaw members in an open configuration;

FIG. 2B is an enlarged, perspective view of the end effector of FIG. 1depicted with the pair of jaw members in a closed configuration;

FIG. 3A is a perspective view of the end effector and elongated shaft ofFIG. 1 with parts separated;

FIG. 3B is cross-sectional view taken along line 3B-3B of FIG. 3Ashowing a distal portion of the electrosurgical forceps of FIG. 1depicting a tube guide;

FIG. 4 is a proximally-facing, perspective view of a rotation knobdepicting a passageway for receiving the elongated shaft of FIG. 1;

FIG. 5 is a cross-sectional, perspective view of the end effector ofFIG. 1;

FIG. 6 is a partial, proximal-facing perspective view of a distalportion of a jaw actuation mechanism of the end effector of FIG. 1;

FIG. 7 is a partial, distal-facing perspective view of distal portion ofa knife actuation mechanism of the end effector of FIG. 1;

FIG. 8A is a perspective view of a lower jaw member of the end effectorof FIG. 1;

FIG. 8B is a perspective view of a tissue sealing plate and atissue-dissecting electrode of the lower jaw member of FIG. 8A;

FIG. 9 is a cross-sectional, perspective view of the lower jaw member ofFIG. 8;

FIG. 10 is a perspective view of a proximal portion of the instrument ofFIG. 1 with a portion of the housing removed revealing internalcomponents;

FIG. 11 is a partial, side view of a proximal portion of the instrumentof FIG. 1;

FIG. 12A is a perspective view of a proximal portion of the knifeactuation mechanism of the end effector of FIG. 1;

FIG. 12B is a cross-sectional, side view of a knife collar of the knifeactuation mechanism of the end effector of FIG. 1;

FIG. 13A is a side view of the proximal portion of the instrument ofFIG. 10 depicting a movable handle in a separated position with respectto a stationary handle, which corresponds to the open configuration ofthe end effector depicted in FIG. 2A, and a knife trigger in a separatedconfiguration with respect to the stationary handle, which correspondsto an un-actuated or proximal configuration of a knife with respect tothe jaw members;

FIG. 13B is a side view of the proximal portion of the instrument ofFIG. 10 depicting the movable handle in an intermediate position withrespect to the stationary handle, which corresponds to a first closedconfiguration of the end effector wherein the jaw members encounter oneanother;

FIG. 13C is a side view of the proximal portion of the instrument ofFIG. 10 depicting the movable handle in an approximated configurationwith respect to the stationary handle, which corresponds to a secondclosed configuration of the end effector wherein the jaw members applyan appropriate pressure to generate a tissue seal; and

FIG. 13D is a side view of the proximal portion of the instrument ofFIG. 10 depicting the knife trigger in an actuated configuration, whichcorresponds to an actuated or distal position of the knife with respectto the jaw members.

DETAILED DESCRIPTION

Referring initially to FIG. 1, an electrosurgical forceps 100 generallyincludes a housing 112 that supports various actuators thereon forremotely controlling an end effector 114 through an elongated shaft 116.Although this configuration is typically associated with instruments foruse in laparoscopic or endoscopic surgical procedures, various aspectsof the present disclosure may be practiced with traditional openinstruments and in connection with endoluminal procedures as well. Thehousing 112 is constructed of a left housing half 112 a and a righthousing half 112 b. The left and right designation of the housing halves112 a, 112 b refer to the respective directions as perceived by anoperator using the forceps 100. The housing halves 112 a, 112 b may beconstructed of sturdy plastic, and may be joined to one another byadhesives, ultrasonic welding or other suitable assembly methods.

To mechanically control the end effector 114, the housing 112 supports astationary handle 120, a movable handle 122, a trigger 126 and arotation knob 128. The movable handle 122 is operable to move the endeffector 114 between an open configuration (FIG. 2A) wherein a pair ofopposed jaw members 130, 132 are disposed in spaced relation relative toone another, and a closed configuration (FIG. 2B) wherein the jawmembers 130, 132 are approximated. Approximation of the movable handle122 with the stationary handle 120 serves to move the end effector 114to the closed configuration and separation of the movable handle 122from the stationary handle 120 serves to move the end effector 114 tothe open configuration. The trigger 126 is operable to extend andretract a knife blade 156 (see FIGS. 2A and 2B) through the end effector114 when the end effector 114 is in the closed configuration. Therotation knob 128 serves to rotate the elongated shaft 116 and the endeffector 114 about a longitudinal axis A-A extending through the forceps114.

To electrically control the end effector 114, the stationary handle 120supports a depressible button 137 thereon, which is operable by the userto initiate and terminate the delivery of electrosurgical energy (e.g.,RF energy) to the end effector 114. The depressible button 137 ismechanically coupled to a switch 136 (FIGS. 13A-13D) disposed within thestationary handle 120 and is engageable by a button activation post 138extending from a proximal side of the moveable handle 122 upon proximalmovement of the moveable handle 122 to an actuated or proximal position(FIG. 13C). The switch 136 is in electrical communication with anelectrosurgical generator 141 via suitable electrical wiring (notexplicitly referenced) extending from the housing 112 through a cable143 extending between the housing 112 and the electrosurgical generator141. The switch 136 may be any suitable switch capable of electricallycoupling the generator 141 to the end effector 114. The generator 141may include devices such as the LigaSure® Vessel Sealing Generator andthe ForceTriad® Generator sold by Covidien. The cable 143 may include aconnector (not shown) thereon such that the forceps 100 may beselectively coupled electrically to the generator 141.

The upper and lower jaw members 130, 132 are electrically coupled tocable 143, and thus to the generator 141 (e.g., via respective suitableelectrical wiring extending through the elongated shaft 116) to providean electrical pathway to a pair of electrically conductive,tissue-engaging sealing plates 148, 150 disposed on the lower and upperjaw members 132, 130, respectively, and a tissue-dissecting electrode149 disposed on lower jaw member 132. The sealing plate 148 of the lowerjaw member 132 opposes the sealing plate 150 of the upper jaw member 130and the tissue-dissecting electrode 149 extends distally from adistal-most end of jaw member 132. In some embodiments, the sealingplates 148 and 150 are electrically coupled to opposite terminals, e.g.,positive or active (+) and negative or return (−) terminals associatedwith the generator 141. Thus, bipolar energy may be provided through thesealing plates 148 and 150 to tissue. Alternatively, the sealing plates148 and 150 may be configured to deliver monopolar energy to tissue. Ina monopolar configuration, one or both sealing plates 148 and 150deliver electrosurgical energy from an active terminal, e.g., (+), whilea return pad (not shown) is placed generally on a patient and provides areturn path to the opposite terminal, e.g., (−), of the generator 141.

Each jaw member 130, 132 includes a jaw insert 140 (FIG. 9) and aninsulator 142 that serves to electrically insulate the sealing plates150, 148 from the jaw insert 140 of the jaw members 130, 132,respectively. Jaw member 132 includes an insulator 146 that serves toelectrically insulate tissue-dissecting electrode 149 from sealing plate148 and jaw insert 140 (FIG. 9). Insulator 146 also serves to spacetissue-dissecting electrode 149 from sealing plate 148.

In some embodiments, tissue-dissecting electrode 149 and sealing plate148 are electrically coupled to opposite terminals, e.g., positive oractive (+) and negative or return (−) terminals associated with thegenerator 141 such that bipolar energy is delivered to tissue-dissectingelectrode 149 and sealing plate 148 to generate an energy potentialtherebetween for dissecting tissue contacted by tissue-dissectingelectrode 149 and/or sealing plate 148 with bipolar electrosurgicalenergy. In this manner, an energy potential may be generated betweentissue-dissecting electrode 149 and either sealing plate 148 or sealingplate 150 or both sealing plates 148, 150. That is, both sealing plates148, 150 may be energized together or separately, with the same ordifferent polarity (e.g., (+) or (−)), or any combination thereof. As apractical example, during a tissue dissecting procedure, sealing plates148, 150 may both be energized with the same polarity (e.g., (+)) andtissue-dissecting electrode 149 may be energized with the oppositepolarity (e.g., (−)) to generate an energy potential betweentissue-dissecting electrode 149 and one or both of sealing plates 148,150 (e.g., one of the sealing plates may be electrically deactivatedduring tissue dissection) such that tissue-dissecting electrode 149 maybe utilized to dissect tissue using bipolar electrosurgical energy.Alternatively, tissue-dissecting electrode 149 may be configured todeliver monopolar energy to tissue. In a monopolar configuration,tissue-dissecting electrode 149 delivers electrosurgical energy from anactive terminal, e.g., (+), while a return pad (not shown) is placedgenerally on a patient and provides a return path to the oppositeterminal, e.g., (−), of the generator 141.

Electrosurgical energy may be delivered to tissue through the sealingplates 148, 150 to effect a tissue seal. During tissue sealing,tissue-dissecting electrode 149 may be electrically deactivated. Once atissue seal is established, a knife blade 156 having a sharpened distaledge 157 may be advanced through a knife channel 158 defined in one orboth jaw members 130, 132 to transect the sealed tissue. Although theknife blade 156 is depicted in FIG. 2A as extending from the elongatedshaft 116 when the end effector 114 is in an open configuration, in someembodiments, extension of the knife blade 156 into the knife channel 158when the end effector 114 is in the open configuration is prevented, asdiscussed below with reference to FIGS. 13A-13D. In some embodiments,sealing plates 148, 150 may conduct electrosurgical energy throughtissue grasped therebetween to electrosurgically cut tissue. With thispurpose in mind, the generator 141 is configured to generate variouselectrosurgical waveforms suitable for use in performing variouselectrosurgical procedures (e.g., tissue cutting, tissue sealing, tissuecoagulation, etc.). In use, for example, the generator 141 may provide a“tissue sealing” electrosurgical waveform to sealing plates 148, 150 forsealing tissue grasped therebetween and subsequently provide a “tissuecutting” electrosurgical waveform to sealing plates 148, 150 forelectrosurgically cutting the sealed tissue grasped therebetween.

Referring now to FIGS. 2A-3A, the end effector 114 may be moved from theopen configuration (FIG. 2A) wherein tissue (not shown) is receivedbetween the jaw members 130, 132, and the closed configuration (FIG.2B), wherein the tissue is clamped and treated. The jaw members 130, 132pivot about a pivot pin 144 to move the end effector 114 to the closedconfiguration of FIG. 2B wherein the sealing plates 148, 150 provide apressure to tissue grasped therebetween. In some embodiments, to providean effective tissue seal, a pressure within a range between about 3kg/cm2 to about 16 kg/cm2 and, desirably, within a working range ofabout 7 kg/cm2 to about 13 kg/cm2, may be applied to the tissue. Also,in the closed configuration, a separation or gap distance is maintainedbetween the sealing plates 148, 150 by an array of stop members 154(FIG. 2A) disposed on or adjacent the sealing plates 148, 150. The stopmembers 154 contact opposing surfaces on the opposing jaw member 130,132 and prohibit further approximation of the sealing plates 148, 150.In some embodiments, to provide an effective tissue seal, an appropriategap distance of about 0.001 inches to about 0.010 inches and, desirably,between about 0.002 inches to about 0.005 inches, may be provided. Insome embodiments, the stop members 154 are constructed of aheat-resistant ceramic deposited onto the jaw members 130, 132. In otherembodiments, the stop members 154 are constructed of an electricallynon-conductive plastic molded onto the jaw members 130, 132, e.g., by aprocess such as overmolding or injection molding.

Referring to FIG. 3A, the elongated shaft 116 includes variouslongitudinal components that operatively couple the end effector 114 tothe various actuators supported by the housing 112 (FIG. 1). An outershaft member 160 defines an exterior surface of the elongated shaft 116and houses other components therein as described below. The outer shaftmember 160 is configured for longitudinal motion with respect to aninner actuation member 180 axially received within the outer shaftmember 160. The inner actuation member 180 may be a rod, a shaft, atube, folded metal, stamped metal, or other suitable structure. Aproximal portion 166 of the outer shaft member 160 is configured forreceipt within the housing 112 (FIG. 1), and includes features foroperatively coupling the outer shaft member 160 to various elements ofthe housing 112. More specifically, the proximal portion 166 of theouter shaft member 160 includes, in order from distal to proximal, alongitudinal slot 169 to couple the outer shaft member 160 to therotation knob 128, a longitudinal knife slot 168 defined therethrough, apair of opposing distal locking slots 161 a, 161 b, and a pair ofopposing proximal locking slots 171 a, 171 b. The connection establishedbetween the outer shaft member 160 and the rotation knob 128 isdescribed below with reference to FIG. 4.

A distal portion 186 of the inner actuation member 180 includes alongitudinal recess 190 defined therein that provides clearance for thepivot pin 144 and thus, permits longitudinal reciprocation of the pivotpin 144 (via longitudinal reciprocation of the outer shaft member 160)independent of the inner actuation member 180. Distal to thelongitudinal recess 190, a cam pin 192 is mechanically coupled (e.g.,via welding, friction-fit, laser welding, etc.) to the distal portion186 of the inner actuation member 180. A proximal portion 188 of theinner actuation member 180 includes a washer 187 coupled thereto (FIG.10). The washer 187 is captured within the housing 112 and serves toprohibit longitudinal motion of the inner actuation member 180 parallelto the longitudinal axis A-A.

The pivot pin 144 extends through a proximal portion of each of the jawmembers 130, 132 to pivotally support the jaw members 130, 132 at thedistal end of the inner actuation member 180. A proximal portion of eachof the jaw members 130, 132 includes two laterally spaced parallelflanges or “flags” 130 a, 130 b and 132 a, 132 b respectively, extendingproximally from a distal portion of the jaw members 130 and 132 (FIGS.3A, 5, and 7-9). A lateral cam slot 130 c and a lateral pivot bore 130 dextend through each of the flags 130 a, 130 b of the upper jaw member130 (FIG. 3A). Similarly, a lateral cam slot 132 c and a lateral pivotbore 132 d extend through each of the flags 132 a, 132 b of the lowerjaw member 132 (FIGS. 8 and 9). The pivot bores 130 d, 132 d receive thepivot pin 144 in a slip-fit relation that permits the jaw members 130,132 to pivot about the pivot pin 144 to move the end effector 114between the open and closed configurations (FIGS. 2A and 2B,respectively).

A knife rod 102 is coupled (e.g., via welding) at a distal-most end tothe sharpened knife blade 156 and includes an angled proximal end 108that provides a mechanism for operatively coupling the knife rod 102 tothe trigger 126. In some embodiments, the angled proximal end 108 of theknife rod 102 is formed by bending the knife rod 102 ninety degrees atits proximal end during manufacturing. The connection between the kniferod 102 and the trigger 126 is described in detail below with referenceto FIGS. 10, 11, 12A, and 12B. The sharpened distal edge 157 of theknife blade 156 may be applied to the distal end of the knife blade 156using a variety of manufacturing techniques such as, for example,grinding, coining, electrochemical etching, electropolishing, or othersuitable manufacturing technique, for forming sharpened edges.

Referring to FIGS. 3A and 3B, a tube guide 109 is disposed within theouter shaft member 160 and includes a lumen 107 axially disposedtherethrough. The inner actuation member 180 is received within theguide lumen 107, which serves to orient and align the inner actuationmember 180 within the outer shaft member 160. The knife rod 102 isreceived within a longitudinal guide recess 105 formed in the outersurface of the guide tube 109. The guide recess 105 serves to guidelongitudinal motion of the knife rod 102 within the outer shaft member160 and to radially space the knife rod 102 from the inner actuationmember 180 to prevent the inner actuation member 180 from interferingwith reciprocal motion of the knife rod 102. The tube guide 109 mayinclude one or more suitable lumens axially disposed therethrough thatserve to receive electrical wiring (not shown) configured toelectrically connect sealing plates 148, 150 and tissue-dissectingelectrode 149 to the generator 141 through cable 143.

Referring now to FIG. 4, the rotation knob 128 includes a distal portion125 extending distally therefrom and a passageway 129 definedtherethrough for receiving the outer shaft member 160. The passageway129 has a generally circular profile corresponding to the circularprofile of the outer shaft member 160. The passageway 129 includes alongitudinal keying member 124 that is configured to align with and beseated within longitudinal slot 169 (FIG. 3A) of the outer shaft member160. The keying member 124 projects laterally inward along the length ofpassageway 129 such that the insertion of the outer shaft member 160into the passageway 129 of the rotation knob 128 operatively couples theouter shaft member 160 to the rotation knob 128. Rotational motionimparted to the rotation knob 128 may thus impart rotational motion toeach of the components of the elongated shaft 116, and to the endeffector 114, which is coupled thereto. As shown in FIGS. 10, 11, and13A-13D, the rotation knob 128 is supported in the housing 112 and, asshown in FIG. 1, extends radially outward from opposing sides of thehousing 112 (only shown extending radially outward from housing half 112b).

Referring now to FIG. 5, the end effector 114 is coupled to the distalend of the inner actuation member 180 by the cam pin 192. The cam pin192 represents a longitudinally stationary reference for longitudinalmovement of the outer shaft member 160 and the knife rod 102. The campin 192 extends through the flags 132 a, 132 b of the lower jaw member132 and the flags 130 a and 130 b of the upper jaw member 130.

Referring now to FIG. 6, the end effector 114 is shown in the openconfiguration. Since the inner actuation member 180 is coupled to thecam pin 192, when the outer shaft member 160 (removed from view in FIG.6 for clarity) is in an unactuated or distal position such that theinner actuation member 180 is in a proximal position relative to theouter shaft member 160, the cam pin 192 is located in a proximalposition in cam slots 130 c and 132 c defined through the flags 130 a,130 b, 132 a, 132 b of the jaw members 130, 132, respectively.

The outer shaft member 160 may be drawn proximally relative to the inneractuation member 180 and the cam pin 192 to move the end effector 114 tothe closed configuration (see FIG. 2B). Since the longitudinal positionof the cam pin 192 is fixed, and since the cam slot 130 c is obliquelyarranged with respect to the longitudinal axis A-A, proximal retractionof the outer shaft member 160 induces distal translation of the cam pin192 through the cam slots 130 c, 132 c such that the jaw member 130pivots toward jaw member 132 about the pivot pin 144. Conversely, whenthe end effector 114 is in the closed configuration, longitudinaltranslation of the outer shaft member 160 in a distal direction inducesproximal translation of the cam pin 192 through the cam slots 130 c, 132c such that jaw member 130 pivots away from jaw member 132 toward theopen configuration.

In some embodiments, the inner actuation member 180 may be configured tomove relative to the outer shaft member 160 to move the end effector 114between the open and closed configurations. In this scenario, themoveable handle 122 may be operably coupled to the inner actuationmember 180 and the washer 187 coupled to the proximal portion 188 of theinner actuation member 180 may be removed such that the inner shaftmember 180 is free to move longitudinally along the longitudinal axisA-A upon actuation of the moveable handle 122. Proximal retraction ofthe inner actuation member 180 may induce proximal translation of thecam pin 192 through the cam slots 130 c, 132 c such that the jaw member130 pivots away from jaw member 132 about the pivot pin 144 toward theopen configuration. Conversely, when the end effector 114 is in the openconfiguration, longitudinal translation of the inner actuation member180 in a distal direction induces distal translation of the cam pin 192through the cam slots 130 c, 132 c such that jaw member 130 pivotstoward jaw member 132 toward the closed configuration.

Referring now to FIG. 7, the pins 144, 192 do not interfere with thereciprocal motion of the knife blade 156. A proximal portion of theinsulator 142 forms a blade guide 152 (also see FIGS. 5, 8, and 9) thatserves to align the knife blade 156 such that the knife blade 156readily enters the knife channel 158 defined in the jaw members 130, 132(jaw member 130 removed from view in FIG. 7 for clarity).

Referring now to FIGS. 8A, 8B, and 9, the lower jaw member 132 isconstructed of a jaw insert 140, insulators 142, 146, a sealing plate148, and a tissue-dissecting electrode 149. The flags 132 a, 132 b ofthe jaw member 132 define a proximal portion of the jaw insert 140 and agenerally u-shaped profile of the jaw insert 140 extends distally tosupport the tissue engaging portion of the jaw member 132. Upper jawmember 130 includes a sealing plate 150, a jaw insert 140, and aninsulator 142.

The insulator 142 of jaw members 130, 132 as well as the insulator 146of jaw member 132 may be constructed of an electrically insulativeplastic such as a polyphthalamide (PPA) (e.g., Amodel®), polycarbonate(PC), acrylonitrile butadiene styrene (ABS), a blend of PC and ABS,nylon, ceramic, silicone, etc. As shown in FIG. 8B, an underside of adistal end of sealing plate 148 is formed to at least partially surroundthe insulator 146 to secure the insulator 146 to the underside ofsealing plate 148. Insulator 146 is, in turn, secured totissue-dissecting electrode 149 (e.g., via adhesive, overmolding, etc.)to couple tissue-dissecting electrode 149 to jaw member 132 whilemaintaining tissue-dissecting electrode 149 in spaced relation withsealing plate 148. Additionally or alternatively, insulator 146 may besecured to the underside of sealing plate 148 via any suitable methodincluding, without limitation, adhesive or overmolding. In someembodiments, insulator 146 may be formed of silicone or a silicone-basedmaterial that has a high melting temperature. Once tissue-dissectingelectrode 149 is secured to jaw member 132 via insulator 146, theinsulator 142 may be overmolded onto the jaw insert 140 in either asingle-shot or a two-shot injection molding process to at leastpartially encapsulate insulator 146 and to couple sealing plate 148 tojaw member 132 in spaced relation with its jaw insert 140, as depictedin FIG. 9. Substantially as described above with respect to sealingplate 148, the insulator 142 may be overmolded onto the jaw insert 140of jaw member 130 in either a single-shot or a two-shot injectionmolding process such that sealing plate 150 is coupled to jaw member 130and in spaced relation with its jaw insert 140. Additionally oralternatively, the insulator 142 may be mechanically coupled to the jawinsert 140, e.g., pressed, snapped, glued, etc. Various features may bemolded into the insulator 142 that facilitate the attachment of thesealing plates 148, 150 to the jaw inserts 140. For example, tabs may beprovided that permit a snap-fit attachment, or ridges may be formed thatpermit ultrasonic welding of the sealing plates 148, 150 onto theinsulators 142. In some embodiments, the insulator 142 on the lower jawmember 132 forms a tissue stop 142 a extending therefrom adjacent to theknife channel 158 and proximal to the sealing plate 148. The tissue stop142 a serves to prevent tissue from entering the distal end of the outershaft member 160 and to prevent splay of the flags 130 a, 130 b of theupper jaw member 130. In some embodiments, the tissue stop 142 a may beformed by the insulator 142 on the upper jaw member 130 or on both theupper jaw member 130 and the lower jaw member 132. The tissue stop 142 amay also serve to align the knife blade 156 as the knife blade 156enters the knife channel 158 defined in the jaw members 130, 132.

Referring now to FIG. 8B, in some embodiments, an underside of sealingplate 148 includes a flex circuit 147 disposed thereon. Flex circuit 147extends between a proximal portion of sealing plate 148 andtissue-dissecting electrode 149 to electrically connecttissue-dissecting electrode 149 to suitable electrical wiring (notshown) that, in turn, serves to electrically connect tissue-dissectingelectrode 149 to generator 141. Flex circuit 147 may be encapsulated bya protective material such as, for example, polyimide, and secured tothe underside of sealing plate 148 prior to the overmolding of insulator142 onto the jaw insert 140 of jaw member 132. In this scenario, flexcircuit 147 and sealing plate 148 may be electrically connected toseparate electrical wires (not shown) that, in turn, electricallyconnect flex circuit 147 and sealing plate 148 to separate terminals,e.g., positive or active (+) and negative or return (−) terminalsassociated with the generator 141.

Referring now to FIG. 10, the connection of the movable handle 122 andthe knife trigger 126 to the longitudinally movable components of theelongated shaft 116 is described. The movable handle 122 may bemanipulated to impart longitudinal motion to the outer shaft member 160,and the knife trigger 126 may be manipulated to impart longitudinalmotion to the knife rod 102. As discussed above, longitudinal motion ofthe outer shaft member 160 serves to move the end effector 114 betweenthe open configuration of FIG. 2A and the closed configuration of FIG.2B, and longitudinal motion of the knife rod 102 serves to move knifeblade 156 through knife channel 158 (FIG. 2A).

The movable handle 122 is operatively coupled to the outer shaft member160 by a clevis 178 defined at an upper end of the movable handle 122.The clevis 178 is pivotally supported on the housing 112. The clevis 178extends upwardly about opposing sides of a drive collar 184 (FIG. 11)supported on the outer shaft member 160 and includes rounded drivesurfaces 197 a and 197 b thereon. Drive surface 197 a engages aproximal-facing surface of a distal spring washer 184 a and drivesurface 197 b engages a distal facing surface of a proximal rim 184 b ofthe drive collar 184 (FIG. 11). The distal spring washer 184 a engages aproximal facing surface of a distal spring stop 184 c that, in turn,engages the opposing distal locking slots 161 a, 161 b (FIG. 3A)extending through the proximal portion 166 (FIG. 3A) of the outer shaftmember 160 to couple the distal spring stop 184 c to the outer shaftmember 160. The drive surfaces 197 a, 197 b are arranged along thelongitudinal axis A-A such that pivotal motion of the movable handle 122induces corresponding longitudinal motion of the drive collar 184 (FIG.11) along the longitudinal axis A-A.

Referring now to FIG. 11, proximal longitudinal motion may be impartedto the outer shaft member 160 by pushing the proximal rim 184 b of thedrive collar 184 proximally with the movable handle 122 (FIG. 10) asindicated by arrow D4 (FIG. 11). A spring 189 is constrained between aproximal facing surface of the drive collar 184 and a proximal springstop 115. The proximal spring stop 115 engages the opposing proximallocking slots 171 a, 171 b (FIG. 3A) extending through the proximalportion 166 (FIG. 3A) of the outer shaft member 160 to couple theproximal spring stop 115 to the outer shaft member 160. Thus, theproximal spring stop 115 serves as a proximal stop against which spring189 compresses.

Distal longitudinal motion is imparted to the outer shaft member 160 bydriving the drive collar 184 distally with the movable handle 122.Distal longitudinal motion of the drive collar 184 induces acorresponding distal motion of the outer shaft member 160 by virtue ofthe coupling of the drive collar 184 to opposing distal locking slots181 a, 181 b extending through the proximal portion 166 of the outershaft member 160 (FIG. 3A).

Proximal longitudinal motion of the outer shaft member 160 draws jawmember 132 proximally such that the cam pin 192 advances distally topivot jaw member 130 toward jaw member 132 to move the end effector 114to the closed configuration as described above with reference to FIG. 6.Once the jaw members 130 and 132 are closed, the outer shaft member 160essentially bottoms out (i.e., further proximal movement of the outershaft member 160 is prohibited since the jaw members 130, 132 contactone another). Further proximal movement of the movable handle 122 (FIG.10), however, will continue to move the drive collar 184 proximally.This continued proximal movement of the drive collar 184 furthercompresses the spring 189 to impart additional force to the outer shaftmember 160, which results in additional closure force applied to tissuegrasped between the jaw members 130, 132 (see FIG. 2B).

Referring again to FIG. 10, the trigger 126 is pivotally supported inthe housing 112 about a pivot boss 103 protruding from the trigger 126.The trigger 126 is operatively coupled to the knife rod 102 by a knifeconnection mechanism 104 such that pivotal motion of the trigger 126induces longitudinal motion of the knife rod 102. The knife connectionmechanism 104 includes upper flanges 126 a, 126 b of the trigger 126 anda knife collar 110.

Referring now to FIGS. 11, 12A, and 12B, the knife collar 110 includes apair of integrally formed pin bosses 139 a, 139 b extending fromopposing sides thereof. As shown by FIG. 12B, the knife collar 110includes an interior circular channel 113 that captures the angledproximal end 108 of the knife rod 102 to couple the knife rod 102 to theknife collar 110. Upon longitudinal motion of the outer shaft member160, the angled proximal end 108 of the knife rod 102 translateslongitudinally within knife slot 168 (FIG. 3A) of the outer shaft member160 such that the longitudinal motion of outer shaft member 160 isunimpeded by the angled proximal end 108 of the knife rod 102. Uponrotation of the elongated shaft 116 and end effector 114 about thelongitudinal axis A-A via the rotation knob 128 (FIG. 1), the angledproximal end 108 of the knife rod 102 freely rotates within the interiorcircular channel 113 of the knife collar 110 such that the outer andinner actuation members 160 and 180 (removed from view in FIG. 12B forclarity), and the knife rod 102 rotate within the knife collar 110 aboutthe longitudinal axis A-A. In this way, the knife collar 110 serves as astationary reference for the rotational movement of the outer shaftmember 160, the inner actuation member 180, and the knife rod 102.

Referring again to FIG. 10, the upper flanges 126 a, 126 b of thetrigger 126 include respective slots 127 a, 127 b defined therethroughthat are configured to receive the pin bosses 139 a, 139 b,respectively, of the knife collar 110 such that pivotal motion of thetrigger 126 induces longitudinal motion of the knife collar 110 and,thus, the knife rod 102 by virtue of the coupling of knife rod 102 tothe knife collar 110.

Referring now to FIGS. 11 and 12A, when the trigger 126 is moved toinduce motion of the knife collar 110 in order to translate the blade156 through the knife channel 158, the knife collar 110 translates alongthe outer shaft member 160 in the direction of arrow A5 to abut a spring119 such that spring 119 compresses against the distal portion 125 ofthe rotation knob 128 (FIG. 12A). The spring 119 biases the knife collar110 proximally along the outer shaft member 160.

Referring now to FIGS. 13A, 13B, 13C and 13D, a sequence of motions maybe initiated by moving the movable handle 122 to induce motion of theouter shaft member 160 in order to close the jaws 130, 132, and bymoving the trigger 126 to induce motion of the knife collar 110 in orderto translate the blade 156 through the knife channel 158. Initially,both the moveable handle 122 and the knife trigger 126 are in a distalor un-actuated position as depicted in FIG. 13A. This arrangement of themoveable handle 122 and trigger 126 sustains the end effector 114 in theopen configuration (FIG. 2A) wherein the jaw members 130, 132 aresubstantially spaced from one another, and the knife blade 156 is in aretracted or proximal position with respect to the jaw members 130, 132.When both the moveable handle 122 and the knife trigger 126 are in thedistal, un-actuated position, pivotal motion of the knife trigger 126 ina proximal direction, i.e., toward the stationary handle 120, ispassively prohibited by interference between the trigger 126 andmoveable handle 122. This interference prohibits advancement of theknife blade 156 through the knife channel 158 when the end effector 114is in the open configuration.

The movable handle 122 may be moved from the distal position of FIG. 13Ato the intermediate position depicted in FIG. 13B to move the jawmembers 130, 132 to the closed configuration (FIG. 2B). As the movablehandle 122 pivots in the direction of arrow M1 (FIG. 13B), the drivesurface 197 b of the movable handle 122 engages the proximal rim 184 bof the drive collar 184. The drive collar 184 is driven proximally suchthat the spring 189 biases the proximal spring stop 115 and, thus, theouter shaft member 160 is driven proximally in the direction of arrow M2(FIG. 13B). As discussed above with reference to FIG. 6, proximalmovement of the outer shaft member 160 serves to translate the cam pin192 distally though the cam slots 130 c, 132 c (FIG. 3A) of the jawmembers 130, 132, respectively, and thus pivot jaw member 130 toward jawmember 132 (FIG. 2B). As the jaw members 130, 132 engage one another andno further pivotal movement of the jaw members 130, 132 may be achieved,further distal movement of the cam pin 192 and further proximal movementof the outer shaft member 160 are prevented.

As the movable handle 122 is moved from the distal position of FIG. 13Ato the intermediate position depicted in FIG. 13B, a tooth 122 aextending proximally from an upper portion of the moveable handle 122engages a clicker tab 120 a supported within the stationary handle 120to generate a tactile and/or an audible response. The clicker tab 120 amay be constructed of a plastic film, sheet metal, or any suitablematerial configured to generate a “clicking” sound as the clicker tab120 a is engaged and disengaged by the tooth 122 a. This responsegenerated by the clicker tab 120 a corresponds to a complete grasping oftissue between the jaw members 130, 132 and serves to indicate to thesurgeon that further pivotal motion of the moveable handle 122 in aproximal direction, i.e., toward the stationary handle 120, will causethe button activation post 138 to engage the depressible button 137. Asthe moveable handle 122 is moved from the intermediate position of FIG.13B to the actuated or proximal position of FIG. 13C, the buttonactivation post 138 depresses the depressible button 137, therebyactivating the switch 136 disposed within the stationary handle 120 toinitiate the delivery of electrosurgical energy to the end effector 114to generate a tissue seal.

As the movable handle 122 is moved from the intermediate position ofFIG. 13B to the actuated or proximal position of FIG. 13C, the pressureapplied by the jaw members 130, 132 is increased. As the movable handle122 pivots further in the direction of arrow M3 (FIG. 13C), the drivesurface 197 b presses the proximal rim 184 b of the drive collar 184further proximally against the spring 189 in the direction of arrow M4(FIG. 13C). The spring 189 is compressed against the proximal springstop 115, and a tensile force is transmitted through the outer shaftmember 160 to the jaw members 130, 132. The tensile force supplied bythe spring 189 ensures that the jaw members 130, 132 apply anappropriate pressure to effect a tissue seal.

When the movable handle 122 is in the actuated or proximal position, theknife trigger 126 may be selectively moved from the distal position ofFIG. 13C to the proximal position of FIG. 13D to advance the knife blade156 distally through knife channel 158. The knife trigger 126 may bepivoted in the direction of arrow M5 (FIG. 13D), about pivot boss 103 toadvance the flanges 126 a, 126 b of the knife trigger 126 distally inthe direction of arrow M6 such that the pin bosses 139 a, 139 btranslate within respective slots 127 a, 127 b from the position shownin FIGS. 13A-13C to the position shown in FIG. 13D (flange 126 b, pinboss 139 b, and slot 127 b are obstructed from view in FIGS. 13A-13D).Movement of flanges 126 a, 126 b draws the knife collar 110 distally,which induces distal longitudinal motion of the knife rod 102 by virtueof the coupling of the knife rod 102 to the knife collar 110, asdescribed above with reference to FIG. 12B.

The various embodiments disclosed herein may also be configured to workwith robotic surgical systems and what is commonly referred to as“Telesurgery”. Such systems employ various robotic elements to assistthe surgeon in the operating theatre and allow remote operation (orpartial remote operation) of surgical instrumentation. Various roboticarms, gears, cams, pulleys, electric and mechanical motors, etc. may beemployed for this purpose and may be designed with a robotic surgicalsystem to assist the surgeon during the course of an operation ortreatment. Such robotic systems may include, remotely steerable systems,automatically flexible surgical systems, remotely flexible surgicalsystems, remotely articulating surgical systems, wireless surgicalsystems, modular or selectively configurable remotely operated surgicalsystems, etc.

The robotic surgical systems may be employed with one or more consolesthat are next to the operating theater or located in a remote location.In this instance, one team of surgeons or nurses may prep the patientfor surgery and configure the robotic surgical system with one or moreof the instruments disclosed herein while another surgeon (or group ofsurgeons) remotely control the instruments via the robotic surgicalsystem. As can be appreciated, a highly skilled surgeon may performmultiple operations in multiple locations without leaving his/her remoteconsole which can be both economically advantageous and a benefit to thepatient or a series of patients.

The robotic arms of the surgical system are typically coupled to a pairof master handles by a controller. The handles can be moved by thesurgeon to produce a corresponding movement of the working ends of anytype of surgical instrument (e.g., end effectors, graspers, knifes,scissors, etc.) which may complement the use of one or more of theembodiments described herein. The movement of the master handles may bescaled so that the working ends have a corresponding movement that isdifferent, smaller or larger, than the movement performed by theoperating hands of the surgeon. The scale factor or gearing ratio may beadjustable so that the operator can control the resolution of theworking ends of the surgical instrument(s).

The master handles may include various sensors to provide feedback tothe surgeon relating to various tissue parameters or conditions, e.g.,tissue resistance due to manipulation, cutting or otherwise treating,pressure by the instrument onto the tissue, tissue temperature, tissueimpedance, etc. As can be appreciated, such sensors provide the surgeonwith enhanced tactile feedback simulating actual operating conditions.The master handles may also include a variety of different actuators fordelicate tissue manipulation or treatment further enhancing thesurgeon's ability to mimic actual operating conditions.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely as examplesof particular embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

Although the foregoing disclosure has been described in some detail byway of illustration and example, for purposes of clarity orunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the appended claims.

What is claimed is:
 1. An electrosurgical instrument, comprising: anelongated shaft coupled to a housing and defining a longitudinal axis; amovable handle operably coupled to the elongated shaft and configured tomove the elongated shaft along the longitudinal axis; a pair of jawmembers disposed at a distal portion of the elongated shaft, at leastone of the pair of jaw members movable relative to the other jaw memberbetween an open position and a closed position; an inner shaft axiallydisposed within the elongated shaft and having a distal portion coupledto a cam pin configured to be received within a cam slot of at least oneof the jaw members and a proximal portion disposed within the housing,wherein movement of the elongated shaft along the longitudinal axis andrelative to the inner shaft moves the cam slot relative to the cam pinto move at least one of the pair of jaw members between the open andclosed positions; and a tissue-dissecting electrode disposed on one ofthe pair of jaw members and configured to electrosurgically dissecttissue.
 2. The electrosurgical instrument according to claim 1, whereinat least one of the pair of jaw members includes an insulator configuredto electrically insulate the tissue-dissecting electrode.
 3. Theelectrosurgical instrument according to claim 1, wherein thetissue-dissecting electrode and a tissue sealing surface disposed on oneof the pair of jaw members are configured to deliver bipolarelectrosurgical energy to tissue.
 4. The electrosurgical instrumentaccording to claim 1, wherein the tissue-dissecting electrode isconfigured to couple to a return pad and deliver monopolarelectrosurgical energy to tissue.
 5. The electrosurgical instrumentaccording to claim 1, wherein the tissue-dissecting electrode is securedto at least one of the pair of jaw members by an insulator.
 6. Theelectrosurgical instrument according to claim 1, wherein at least one ofthe pair of jaw members includes an electrically conductive tissuesealing surface disposed in spaced relation to the tissue-dissectingelectrode and configured to connect to a source of electrosurgicalenergy.
 7. The electrosurgical instrument according to claim 1, whereinthe tissue-dissecting electrode extends distally from a distal end ofone of the pair of jaw members.
 8. The electrosurgical instrumentaccording to claim 1, wherein the tissue-dissecting electrode isconfigured to dissect tissue when the at least one of the pair of jawmembers is in the open position.
 9. The electrosurgical instrumentaccording to claim 1, further comprising a knife configured to movethrough a knife channel extending along at least one of the pair of jawmembers to cut tissue.
 10. The electrosurgical instrument according toclaim 1, further comprising a switch extending from the housing andconfigured to be actuated by the movable handle to control delivery ofelectrosurgical energy to at least one of the tissue-dissectingelectrode or the pair of jaw members.
 11. The electrosurgical instrumentaccording to claim 1, wherein one of the pair of jaw members ismechanically coupled to a distal end of the elongated shaft.
 12. An endeffector for an electrosurgical instrument, comprising: a first jawmember coupled to a distal portion of an elongated shaft; a second jawmember pivotably coupled to the first jaw member and configured to moverelative to the first jaw member between an open position and a closedposition; an electrically conductive tissue sealing surface disposed oneach of the first and second jaw members; a tissue-dissecting electrodedisposed on the second jaw member in spaced relation to the tissuesealing surface of the second jaw member, the tissue-dissectingelectrode configured to electrosurgically dissect tissue; and a cam slotdefined by at least one of the first or second jaw members andconfigured to receive a cam pin mechanically coupled to a distal portionof an inner shaft axially disposed within the elongated shaft such thatlongitudinal movement of the elongated shaft relative to the inner shaftmoves the cam slot relative to the cam pin to move the second jaw memberbetween the open and closed positions.
 13. The end effector according toclaim 12, wherein the second jaw member includes an insulator configuredto electrically insulate the tissue-dissecting electrode from the secondjaw member.
 14. The end effector according to claim 12, wherein thesecond jaw member includes an insulator configured to space thetissue-dissecting electrode from the tissue sealing surface of thesecond jaw member.
 15. The end effector according to claim 12, whereinthe tissue-dissecting electrode and the tissue sealing surface of atleast one of the first or second jaw members are configured to deliverbipolar electrosurgical energy to tissue.
 16. The end effector accordingto claim 12, wherein the tissue-dissecting electrode is configured tocouple to a return pad and deliver monopolar electrosurgical energy totissue.
 17. The end effector according to claim 12, wherein thetissue-dissecting electrode extends distally from a distal end of thesecond jaw member.
 18. The end effector according to claim 12, whereinat least one of the first or second jaw members includes a knife channelconfigured to receive a knife for cutting tissue.
 19. An electrosurgicalinstrument, comprising: an elongated shaft coupled to a housing anddefining a longitudinal axis; a movable handle operably coupled to theelongated shaft and configured to move the elongated shaft along thelongitudinal axis; an end effector disposed at a distal portion of theelongated shaft; an inner shaft axially disposed within the elongatedshaft and having a distal portion coupled to a cam pin configured to bereceived within a cam slot of the end effector and a proximal portiondisposed within the housing, wherein movement of the elongated shaftalong the longitudinal axis and relative to the inner shaft isconfigured to move the cam slot relative to the cam pin to actuate theend effector; and a tissue-dissecting electrode disposed on the endeffector and configured to electrosurgically dissect tissue.